Wireless signaling applications, including optical signaling applications, can be limited by the level of transmit power as well as the level of receiver sensitivity. Improving receiver sensitivity allows for greater link margins for a given transmit power level. Similarly, increasing the transmit power level can increase link margins for a given receiver sensitivity. Extremely high-power laser pulses can be used to improve the performance of many Free-Space Optical (FSO) applications. Examples of FSO applications include, but are not limited to, ranging to cooperative and non-cooperative targets, and communicating by retro-modulation at long ranges and in the presence of atmospheric attenuations.
Optical ranging can be performed, for example, in a system that transmits a modulated or pulsed optical signal towards a target. The system can then receive a signal reflected by the target. The system can determine a range based in part by determining the time for the optical signal to traverse the distance to the target and return. FSO communication systems can modulate an optical source with a data signal. A remote receiver can receive the optical signal to extract the data. Typical FSO communication systems use continuous wave (CW) or on-off keying (OOK) modulation because of their low-optical power.
However, most presently available high-power optical sources, such as those having output optical power levels on the order of kilo watts, have limited FSO applications because of their large sizes, high electrical power consumptions, and eye-safety constraints. A large physical size of an optical source can make the source unsuitable for portable applications. Similarly, high electrical power consumption makes the optical source unsuitable for mobile applications due to the size of an associated power source needed to supply electrical power to the unit. Furthermore, high power optical sources pose potential eye-safety hazards. Additional controls can be added to a high power optical source to help alleviate the eye-safety hazards. However, the additional controls used to satisfy eye-safety constraints typically compound the physical size and power consumption problems associated with presentaly available high power optical sources.
It is desirable to have a high power optical source that is capable of integration into a system for use in a portable application. It would be advantageous to maximize optical power while minimizing physical size and electrical power consumption. Additionally, such an optical source should satisfy safety constraints, such as those associated with eye safety.